The present invention relates to a reluctance rotary machine and, more particularly, to a reluctance rotary machine coupled to an exhaust gas turbine of an internal combustion engine, for example.
There has heretofore been an attempt to drive a generator with an exhaust-gas turbine installed on an internal combustion engine to generate electric power for use as a power supply for various loads in an automobile.
The generator used in such an arrangement is generally of the induction type in which no current is passed through the rotor. The reason for using induction generator is that with a general synchronous generator, there are employed a rotor with coils and brushes interposed between the rotor and a field current supply for supplying current to the rotor coils from a fixed side, and the brushes would fail to be sufficiently strong mechanically on high-speed rotation of the rotor and would be worn or broken so that no electric power could be picked up.
The induction generator is, however, suitable for high-speed rotation as no current is passed through the rotor, and is effective for use as a generator which operates at several tens of thousands revolutions per minute.
With the induction generator, especially with a squirrel-cage rotor which lends itself to high-speed rotation, however, the rotor is of an integral construction including secondary conductors and short-circuit rings connecting the ends of the second conductors, the secondary conductors and the short-circuit rings being formed by casting aluminum in an iron core. On high-speed rotation, the rotor is subjected to undue centrifugal forces acting on the entire circumference thereof to cause the secondary conductors to gradually detach from the iron core and the short-circuit rings until finally the rotor is destroyed.